1. Field of the Invention
The present patent document relates generally to optical scanning devices used to translate the contents of printed documents into electronic format, and more particularly to the control of electrical power to such devices.
2. Description of Related Art
Several different types of light sources or lamps have been incorporated into optical scanners in order to illuminate the item being scanned. Among other things, the choice of lamp type and style is often based upon cost, size, lamp life, light intensity, output spectrum, power requirements, and turn-on time. Such lamps include cold cathode fluorescent, hot cathode fluorescent, xenon, and light emitting diode (LED) light sources.
In modern scanner systems, especially for those using the more popular cold cathode fluorescent lamps, the warm-up time for the scanner""s light source is relatively long. For greater productivity, the scanner should be immediately available for use at any time. In a practical sense, the only technique by which this objective can be met is to leave the light source turned on all the time. However, if the light-source is on continuously, excessive power consumption and a large reduction in lamp operational life will result. As an example, cold cathode fluorescent lamps have an average lamp life of between 10,000 and 15,000 hours prior to burn-out. If a cold cathode lamp is on for only 1,000 hours per year, the operational life of the lamp is approximately 10 to 15 years, and even at 2,000 hours per year, it is 5 to 7.5 years. However, if on continuously, the operational life of the lamp will be reduced to only 14 to 20 months. Thus, there is a significant need to improve the scanner system so as to have, at least in most cases, the light-source warmed up when needed, while reducing degradation in lamp operational life.
Representative embodiments of the teachings of the present patent document provide enhanced capabilities not previously available to aid in the immediate availability for scanning of optical scanning systems, while reducing degradation of lamp operational life and controlling energy consumption. These capabilities provide increased productivity for an operator of such systems.
Representative embodiments of the present patent document incorporate a software program and associated circuitry for controlling the times when the scanner""s exposure lamp is turned on. In another embodiment, a timing circuit is used instead of the software program for controlling the times that the exposure lamp is on. The potential for a reduction in operator perceived lamp warm-up time thus exists, without requiring that the lamp be on continuously. In fact, the system can be set up such that the scanner is on and warmed-up when the operator arrives at work and is turned off after he leaves for the day. The terms lamp and exposure lamp, as used herein, include not only lamps such as the cold cathode fluorescent, hot cathode fluorescent, and xenon lamps, but also other sources of illumination, such as light emitting diodes (LED""s).
Since waiting for the exposure lamp in a scanner system to warm up can be expensive in terms of operator inefficiency, since lamp operational life is reduced in relation to the time the lamp is turned on, since leaving a lamp on continuously consumes increased energy, and since image quality is enhanced by the lamp being fully warmed-up, representative embodiments of the present invention provide needed, enhanced capabilities not previously available. Other aspects and advantages of the representative embodiments of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. The details disclosed in the specification should not be read so as to limit the invention.